• 한국식품과학회지
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• 제29권6호
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• pp.1075-1081
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• 1997

L-Glutamate를 간편하고 단시간에 측정할 수 있는 glutamate sensor를 개발하기 위하여, glutamate oxidase를 여러 가지 membranes에 고정화 시키는데 적합한 조건과. 그 결과로 얻은 효소 membranes의 특성, 개발한 glutamate sensor의 반응특성 및 glutamate sensor의 정확성을 조사하였다. Glutamate oxidase를 membranes에 고정화 하는데 GA 0.25%, BSA 0.3 mg, 효소 사용량 2.0 units이상이 적당하였다. 고정화 효소의 최적 pH는 6.5이었고, chitosan membrane을 사상한 경우 가장 효소활성이 높았다. 그러나 저장 안정성이나 반응시간 등을 고려하여 preactivated nylon에 고정화시킨 효소 membrane을 glutamate sensor 개발에 사용하였다. Glutamate oxidase를 선택한 membrane에 고정화시켜 효소와 glutamate의 반응산물인 암모니아가 nonactin membrane을 이용한 암모니움이온 전극에 의하여 측정되도록 효소 sensor를 구성하였으며, sensor의 반응시간은 약 2분이었다. Preactivated membrane에 고정화된 효소는 $4^{circ}C$에서 2개월간 저장중 안정한 활성을 보였으며, 이를 사용한 glutamate sensor로 약 250회 측정할 때 까지 활성에 별 변화가 없었다, 개발된 glutamate sensor의 glutamate 측정 농도범위는 $0.1{\sim}5\;mM$ 이었다. Glutamate sensor를 체더 치즈중의 L-glutamate 측정에 응용한 결과는 HPLC로 분석한 결과와 높은 상관관계가 있어, 정확성이 인정되었다.

• 대한약리학회지
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• 제29권2호
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• pp.189-193
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• 1993

흰쥐태 뇌간의 세포를 배양하여 glutamate에 6시간까지 노출시 glutamate의 농도 및 노출 시간에 의존적으로 세포내 5-HT 및 5-HIAA의 함량이 감소하였고, 배양액으로 LDH의 유출이 증가하였다. Tetrodotoxin은 glutamate의 작용을 차단하지 못하였다. NMDA 수용체 통로 봉쇄제인 MK-801에 의해 glutamate의 작용이 효과적으로 차단되었고, non-NMDA 길항제인 CNQX는 효과가 없었으므로, serotonin 신경세포에 대한 glutamate의 작용은 NMDA 수용체의 자극에 의한 것으로 사료된다.

• The Korean Journal of Physiology and Pharmacology
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• 제5권6호
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• pp.457-466
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• 2001

Glutamate is the most common excitatory amino acid in the brain. Responsiveness of dendrites to the glutamate greatly varies depending on the application sites. Especially, a point of the maximal response to the glutamate of the dendrite is called as 'hot spot'. In our experiment, the responsiveness of the hot spot to the glutamate was investigated in the CA1 pyramidal neuron of the rat hippocampal slice. CNQX, the antagonist of AMPA receptor, blocked 95% of membrane current to the glutamate focal application $(I_{gl}).$ Train ejection of glutamate on one point of the dendrite increased or decreased the amplitude of $I_{gl}$ with the pattern of train, and the changes were maintained at least for 30 min. In some cases, glutamate train ejection also induced calcium dependent action potentials. To evoke long-term change of synaptic plasticity, we adopted ${\theta}-burst$ in the glutamate train ejection. The ${\theta}-burst$ decreased the amplitude of glutamate response by 60%. However, after ${\theta}-burst$ glutamate train ejection, the calcium dependent action potential appeared. These results indicated that the focal application of glutamate on the neuronal dendrite induced response similar to the synaptic transmission and the trains of glutamate ejection modulated the change of AMPA receptor.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1993년도 제2회 신약개발 연구발표회 초록집
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• pp.46-46
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• 1993

The neuroprotective effect of betaine, one of the , components of Lycii Fructus, on glutamate-induced neurotoxicity in primary cultured chicken brain cells were examined. Betaine was found to attenuate glutamate-induced neurotoxicity at the concentration of 5-10 mM in both morphological and chemical aspects. The pretreament of chicken brain cells with 5-10 mM betaine for 2 hr at the 12th day of culture before the 40 min-exposure to 500${\mu}$M glutamate significantly increased the survival rate of nerve cells in chicken brain. Betaine could also raise the decreased LDH-level due to the neurotoxicity induced with 100${\mu}$M glutamate in chicken braill cells. LDH value was decreased to 63％ of control level in chicken brain cells at the time of 48 hr after the exposure to glutamate. However, the pretreament of chicken brain cells with 5 mM betaine for 2 hr before the exposure to glutamate could prevent the decrease of LDH-level in brain cells showing 90％ of control level. Nevertheless, tile remarkable neuroprotective effect of betaine on the glutamate-inducer in neurotoxicity in cultured chicken brain cells could not be observe when betaine was simultaneously administered with glutamate.

• Archives of Pharmacal Research
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• 제19권2호
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• pp.132-136
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• 1996

Exogenously applied oxygen free radical generating agent, pyrogallol, highly elevated extracellular glutamate accumulation and augmented N-methyl-D-aspartate (NMDA)-induced glutamate accumulation in cerebellar granule neuronal cells, but did not in astrocytes. Superoxide dismutase remarkably decreased the pyrogallol-induced glutamate accumulation, but either NMDA or kainate antagonists did not. In addition, pyrogallol did not affect the NMDAinduced intracellular calcium elevation. Pyrogallol partially blocked glutamate uptake into astrocytes. These results suggest that oxygen free radicals elevate extracellular glutamate accumulation by stimulating the release of glutamate as well as blocking the glutamate uptake.

• Archives of Pharmacal Research
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• 제21권2호
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• pp.113-119
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• 1998

Changes in the release and uptake of glutamate in cerebellar granule and glial cells of offspring of lead-exposed mothers were determined. In cultured cerebellar granule cells exposed to lead for 5 days, glutamate release was less influenced upon N-methyl-D-aspartate (NMDA) stimulation than that in the control. Although the NMDA-stimulated release of glutamate in cerebellar granule cells prepared from lead-exposed first generation pups was not different from that of the control group, the S-nitroso-N-acetylpenicillamine (SNAP)-stimulated release of glutamate in cerebellar granule cells obtained from lead-treated pups was less elevated than that in the control. Furthermore, in cerebellar granule cells obtained from lead-exposed second generations pups, glutamate release did not respond to both NMDA and SNAP stimulation. In cerebellar glial cells exposed to lead, the basal glutamate uptake was not changed. However, the L-trans-pyrollidine-2,4-dicarboxylic acid (PDC)-blocking effects was significantly reduced. In glial cells obtained from lead-exposed pups, the glutamate uptake was also less blocked by PDC than that in the control. Further decreases in PDC-blocking effects were observed in cerebellar glial cells obtained from lead-treated second generation pups compared to those from the control group. These results indicate that lead exposure induces the changes in the sensitivities of the glutamate release and uptake transporter. In addition, these results suggest that lead exposure might affect the intracellular signalling pathway and transmission in glutamatergic nervous system.

• 대한한의학회지
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• 제22권4호
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• pp.45-57
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• 2001

Objectives : The water extract of Gwibitang (GBT) has been traditionally used for treatment of psychologic disease and brain damage in Oriental Medicine, This study was designed to investigate the effect of GBT on the glutamate-induced toxicity of rat C6 glial cells. Methods : The cultured cells were pretreated with GBT and exposed to glutamate, The cell damage was assessed by using MTT assay and Hoechst, IC-l staining, Results : GBT had protective effects in glutamate-induced cytotoxicity, which was revealed as apoptosis characterized by chromatic condensation and the loss of mitochondrial membrane potential in C6 glial cells. However, GBT and glutamate had no effect in the activation of caspase family cysteine proteases including caspase-3, -8 and -9 proteasesin C6 glial ce]]s, GBT significantly recovered the depletion of GSH and inhibited the generation of $H_2O_2$ by glutamate in C6 glial cells. In addition, both GBT and antioxidants such as GSH and NAC protected the glutamate-induced cytotoxicity in C6 glial cells, indicating that GBT possibly has antioxidative effect. Moreover, GBT also inhibited the glutamate-induced degradation of $IkB{\alpha}$ in C6 glial cells, This result suggest that GBT has some inhibitory effects on the transcriptional activation of $NF-_{k}B$. Conclusions : GBT has protective effects in glutamate-induced cytotoxicity via an antioxidative mechanism.

• Journal of Ginseng Research
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• 제24권3호
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• pp.138-142
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• 2000

흰쥐 대뇌겉질로부터 별아교세포를 배양하여 흥분성아미노산인 L-glutamate에 의하여 유발되는 세포종창(astrocytic swelling)에 대한 ginsenosides의 억제효과를 검토하였다. Glutamate(0.5 mM)를 세포에 가하고 1시간동안 배양하면 swelling을 일으켜, 세포내의 물의 용적([$^3$H]OMG의 uptake량으로 측정)은 대조세포에 비하여 약 2배의 증가를 나타냈다. Glutamate와 함께 ginsenosides Rb$_2$와 Rc를 가하고 배양하면 glutamate에 의한 astrocytic swelling이 용량의존적으로 감소하였다. 세포는 Rb$_2$와 Rc(0.5 mg/ml)에 24시간까지 노출시켜도 MTT reduction이 감소하지 않는 것으로 보아 이 ginsenosides에 의한 swelling의 억제효과는 세포막의 손상에 의한 것이 아님을 알 수 있었다. Rb$_2$와 Rc는 glutamate에 의한 세포내 $Ca^{2+}$농도의 상승을 억제하였다. 따라서 Rb$_2$와 Rc는Ca$^{2+}$의 유입을 억제하므로서 glutamate에 의한 astrocytic swelling을 억제하는 것으로 생각된다.

• 대한한방내과학회지
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• 제31권3호
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• pp.586-599
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• 2010

Objective : The water extract of Yukgunja-tang(YGJT) has been traditionally used in treatment of qi deficiency and phlegm in Oriental medicine. However, little is known about the mechanism by which YGJT protects neuronal cells from injury damages. Therefore, this study was designed to evaluate the protective effects of YGJT on C6 glial cells by glutamate-induced cell death. Methods : The present study describes glutamate, which is known as an excitatory neurotransmitter, related with oxidative damages, and YGJT, which shows protective effects against glutamate-induced C6 glial cell death. One of the main mediators of glutamate-induced cytotoxicity was known on the generation of reactive oxygen species(ROS) via activation of NADPH oxidase (NOX). The protective effects of antioxidant(NAC) and NOX inhibitor(apocynin) on the glutamate-induced C6 glial cells were determined by a MTT reduction assay. Result : YGJT inhibited glutamate-induced ROS generation via inhibition of NOX expression on glutamate-stimulated C6 glial cells. Furthermore, YGJT attenuated glutamate-induced caspase activation. These results suggest that YGJT could be a new potential candidate against glutamate-induced oxidative stress and cell death. Conclusion : These findings indicate that in C6 glial cells, ROS plays an important role of glutamate-induced cell death and that YGJT may prevent cell death from glutamate-induced cell death by inhibiting the ROS generation.

• Journal of Veterinary Science
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• 제23권2호
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• pp.26.1-26.12
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• 2022

Background: Glutamate is the main excitatory neurotransmitter. Excessive glutamate causes excitatory toxicity and increases intracellular calcium, leading to neuronal death. Parvalbumin is a calcium-binding protein that regulates calcium homeostasis. Quercetin is a polyphenol found in plant and has neuroprotective effects against neurodegenerative diseases. Objectives: We investigated whether quercetin regulates apoptosis by modulating parvalbumin expression in glutamate induced neuronal damage. Methods: Glutamate was treated in hippocampal-derived cell line, and quercetin or vehicle was treated 1 h before glutamate exposure. Cells were collected for experimental procedure 24 h after glutamate treatment and intracellular calcium concentration and parvalbumin expression were examined. Parvalbumin small interfering RNA (siRNA) transfection was performed to detect the relation between parvalbumin and apoptosis. Results: Glutamate reduced cell viability and increased intracellular calcium concentration, while quercetin preserved calcium concentration and neuronal damage. Moreover, glutamate reduced parvalbumin expression and quercetin alleviated this reduction. Glutamate increased caspase-3 expression, and quercetin attenuated this increase in both parvalbumin siRNA transfected and non-transfected cells. The alleviative effect of quercetin was statistically significant in non-transfected cells. Moreover, glutamate decreased bcl-2 and increased bax expressions, while quercetin alleviated these changes. The alleviative effect of quercetin in bcl-2 family protein expression was more remarkable in non-transfected cells. Conclusions: These results demonstrate that parvalbumin contributes to the maintainace of intracellular calcium concentration and the prevention of apoptosis, and quercetin modulates parvalbumin expression in glutamate-exposed cells. Thus, these findings suggest that quercetin performs neuroprotective function against glutamate toxicity by regulating parvalbumin expression.